Method and Apparatus for Implementing a System-Level Design Tool for Design Planning and Architecture Exploration

ABSTRACT

A method for designing a system on a target device includes mapping a high-level description of the system onto a model of a target device prior to generating a register transfer level description of the system. A visual representation of the mapping is generated.

FIELD

Embodiments of the present invention relate to tools for designingtarget devices and tools for designing systems on target devices. Morespecifically, embodiments of the present invention relate to a methodand apparatus for implementing a system-level design tool for designplanning and architecture exploration.

BACKGROUND

Target devices such as field programmable gate arrays (FPGAs),structured application specific integrated circuits (ASICs), and ASICsare used to implement large systems that may include million of gatesand megabits of embedded memory. The complexity of a large system oftenrequires the use of electronic design automation (EDA) tools to createand optimize a design for the system onto physical target devices. Amongthe procedures performed by EDA tools in a computer aided design (CAD)compilation flow are design generation, synthesis, placement, androuting of the system on the target device.

Modern high-end target device designs aim to support bandwidth-heavyapplications. For example, current generation communications processingdesigns implemented on target devices support 10 Gb to 40 Gb throughput.Future designs will be targeting 100 Gb to 400 Gb and then Tbprocessing. Such applications are enabled by increasing speeds oftransceiver (serial input output) blocks which are keeping pace with theinput output bandwidth needs of applications.

As target device architects create next-generation designs to supportthese high-bandwidth applications, and as system designers attempt toimplement their systems on these target devices, tools for architectureexploration and design planning will play an important role for creatingtarget devices and systems that successfully meet timing requirements.

SUMMARY

A method and apparatus for implementing a system-level design tool forperforming design planning and target device architecture exploration isdisclosed. The system-level design tool allows for design planning anddecision making prior to making key decisions that lock down algorithmsand structures of a design. The system-level design tool may also beused to model designs for the purpose of more effectively architectingnext-generation target devices.

Embodiments of the system-level design tool allow for wire-planning andresource management on a high-level design. Designs may be defined usinga high-level description instead of a detailed hardware description suchas register transfer level. The high-level description may be mapped toone or more target device architectures and the mapping may be output toa user such as a system designer or target device architect to evaluate.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of embodiments of the present invention areillustrated by way of example and are not intended to limit the scope ofthe embodiments of the present invention to the particular embodimentsshown.

FIG. 1 is a flow chart illustrating a method for designing a system on atarget device according to an exemplary embodiment of the presentinvention.

FIG. 2A is a flow chart illustrating a method for performing earlyplanning according to an exemplary embodiment of the present invention.

FIG. 2B is a flow chart illustrating a method for performing earlyplanning with a plurality of target devices according to an exemplaryembodiment of the present invention.

FIG. 3A illustrates an example of a high-level description of a systemdesign implemented in block diagram language according to an embodimentof the present invention.

FIG. 3B illustrates an example of a high-level description of a systemdesign implemented in block diagram form according to an embodiment ofthe present invention.

FIG. 4 is a flow chart illustrating a method for performing latencyplanning according to an exemplary embodiment of the present invention.

FIG. 5 illustrates an exemplary slicing floor plan according to anembodiment of the present invention.

FIG. 6 illustrates an exemplary mapped view showing metrics for resourceuse according to an embodiment of the present invention.

FIG. 7 illustrates a block diagram of a computer system implementing asystem designer according to an embodiment of the present invention.

FIG. 8 illustrates a block diagram of a system designer according to anembodiment of the present invention.

FIG. 9 illustrates an exemplary target device according to an embodimentof the present invention.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, specificnomenclature is set forth to provide a thorough understanding ofembodiments of the present invention. It will be apparent to one skilledin the art that specific details in the description may not be requiredto practice the embodiments of the present invention. In otherinstances, well-known circuits, devices, and programs are shown in blockdiagram form to avoid obscuring embodiments of the present inventionunnecessarily.

Embodiments of the present invention may be used to implement asystem-level design tool that may be used for system design andarchitecture exploration. FIG. 1 illustrates an example where thesystem-level design tool is used in the context of system design. FIG. 1is a flow chart illustrating a method for designing a system on a targetdevice according to an exemplary embodiment of the present invention.The target device may be a field programmable gate array (FPGA),application specific integrated circuit (ASIC), a structured ASIC, orother device. According to one embodiment, the procedure illustrated inFIG. 1 may be performed by a computer aided design (CAD)/electronicdesign automation (EDA) tool implemented on a computer system.

At 101, planning is performed on a system to be implemented on a targetdevice. During system planning, a high-level description of the systemas implemented on the target device is tested, and metrics such as wireuse, congestion, timing, resource allocation, latency, and/or otherparameters are evaluated from the testing. According to an embodiment ofthe present invention, the high-level description of the system is at anabstract level prior to register timing level (RTL) generation. Mappingis performed and a description of the mapping is generated to allow auser to evaluate the system. Based on the evaluation of the mapping, theuser may modify the system and/or modify the target device which thesystem is implemented on. Another mapping and evaluation may beperformed in response to the changes made. System planning may befinalized after the user is satisfied with the evaluation of the system.

Target devices such as FPGAs and structured ASICs have a set of fixedresources with placements and functionality that are limited. Examplesof resources that may be allocated specific locations and fixedfunctionalities include digital signal processing elements, memories,bus interfaces, processor cores, and memory controllers. Otherresources, such as global and regional clocks may limit the placement ofobjects to locations that supply needed functionalities. In contrast,ASICs do not have pre-allocated resources. The planning performed fortarget devices such as FPGAs and structured ASICs takes intoconsideration the pre-placement constraints of objects, and thelimitations imposed by the fixed locations for clocks and input outputs.

It should be appreciated that FPGAs are distinguished from structuredASICs in that they posses pre-constructed interconnect resources.Planning performed for target devices such as FPGAs requires thecapability to model the specific capacity of different interconnectresources available and the demand on those interconnect resourcesimposed by a user's design.

At 102, an RTL description is generated for the system planned at 101.RTL is a design abstraction which models a synchronous digital circuitin terms of the flow of digital signals between hardware registers, andthe logical operations performed on those signals. RTL abstraction isused in hardware description languages (HDLs) such as Verilog and VHDLto create RTL representations of a circuit, from which lower-levelrepresentations and wiring can be derived. According to an embodiment ofthe present invention, the RTL is used to represent the system to beimplemented by the remainder of this process.

At 103, the system is synthesized. Synthesis includes generating a logicdesign of the system to be implemented by the target device. Accordingto an embodiment of the present invention, synthesis generates anoptimized logical representation of the system from the HDL designdefinition. Synthesis also includes mapping the optimized logic design.Mapping includes determining how to implement logic gates and logicelements in the optimized logic representation with specific resourceson the target device. According to an embodiment of the presentinvention, a netlist is generated from mapping. This netlist may be anoptimized technology-mapped netlist generated from the HDL.

At 104, the system is placed. According to an embodiment of the presentinvention, placement involves placing the mapped logical system designon the target device. Placement works on the technology-mapped netlistto produce a placement for each of the functional blocks. According toan embodiment of the present invention, placement includes fitting thesystem on the target device by determining which resources on the logicdesign are to be used for specific logic elements, and other functionblocks determined to implement the system as determined duringsynthesis. Placement may include clustering which involves groupinglogic elements together to form the logic clusters present on the targetdevice.

At 105, the placed design is routed. During routing, routing resourceson the target device are allocated to provide interconnections betweenlogic gates, logic elements, and other components on the target device.Routability optimization may also be performed on the placed logicdesign. According to an embodiment of the present invention, the goal ofroutability optimization is to reduce the amount of wiring used toconnect components in the placed logic design. Routability optimizationmay include performing fanout splitting, logic duplication, logicalrewiring, or other procedures. It should be appreciated that one or moreof the procedures may be performed on the placed logic design.

At 106, an assembly procedure is performed. The assembly procedureinvolves creating a data file that includes information determined bythe procedures described at 101-105. The data file may be a bit streamthat may be used to program a target device. According to an embodimentof the present invention, the procedures illustrated in FIG. 1 may beperformed by an EDA tool executed on a first computer system. The datafile generated may be transmitted to a second computer system to allowthe design of the system to be further processed. Alternatively, thedata file may be transmitted to a second computer system, which may beused to program the target device according to the system design. Itshould be appreciated that the design of the system may also be outputin other forms such as on a display device or other medium. The targetdevice may be programmed with the data file. By programming the targetwith the data file, components on the target device are physicallytransformed to implement the system.

FIG. 2A is a flow chart illustrating a method for performing systemplanning according to an exemplary embodiment of the present invention.The procedures illustrated in FIG. 2A may be used to implement procedure101 shown in FIG. 1 in the context of designing a system. It should beappreciated, however, that the procedures illustrated in FIG. 2A mayalso be used independently for performing architecture exploration inthe design of a target device.

At 201, a system design is identified. According to an embodiment of thepresent invention, the system design is identified from inputs receivedfrom a user. The system design may be a high-level description of thesystem that is not a complete RTL design. The high-level description ofthe system may describe components of the system as high-level blocksand include information regarding their resource usage such as thenumber of logic cells, registers, embedded memories, input outputs andother resources on the target device that they may use. The high-leveldescription of the system may include a description of data pathdescriptions which include the width and speed requirements of data pathbetween the high-level blocks. The high-level description of the systemmay include system-level meta-data that identify how data paths are usedand whether they are mutually exclusive and can be shared. Thesystem-level meta-data may also identify the latency tolerance of thedata paths and whether a data path could be pipelined. The high-leveldescription of the system may include block-level meta-data thatidentifies routing porosity which impacts the expected local use of arouting fabric of a component or high-level block. This allows theamount of routing resources available for global data paths to beassessed. According to an embodiment of the present invention, where thetarget device is an FPGA, the routing fabric may be organized accordingto different hierarchies such as global interconnect lines, localinterconnect lines, and row and column interconnect lines. Theinterconnect lines may serve to route signals between components on theFPGA. It should be appreciated that among and within the hierarchies,the interconnect lines on the FPGA may have varying widths or capacityto support the transport of data.

The block-level meta-data may also include information regarding themaximum frequency of a block, the power consumption of the block, and anumber of high-speed or low-power tiles used in previousimplementations. The high-level description of the system may alsoprovide SystemC or other description of the cycle-accurate/approximatebehavior of a block that may be used in constructing dynamic simulation.

According to an embodiment of the present invention, the high-leveldescription of the system may be entered by a user via a graphical userinterface editor or a text editor. A machine-readable format may beproduced by a tool or entered directly by the user. The high-leveldesign description of the system captures the structure and data flow ofthe system including the high-level block description, data pathdescriptions, system-level meta-data, and block-level meta-data.

FIG. 3A illustrates an example of a high-level description of a systemdesign implemented in block diagram language entered using a text editoraccording to an embodiment of the present invention. The format of thehigh-level description illustrated is YAML. The high-level descriptionof the system design illustrated in FIG. 3A allows for the arbitraryexpression of metadata while also providing formalism to expresshierarchy and structural connectivity of the system. FIG. 3A includes aconnection list which shows a number of links instantiated. The linksincludes a connection between port z of component B and port x ofcomponent A, and connection between port W of component B and port y ofcomponent A. The links represent connections between a source and a sinkthat may be implemented by routing resources on a target device.

FIG. 3B illustrates an example of a high-level description of a systemdesign implemented in block diagram form according to an embodiment ofthe present invention. The block diagram representation of thehigh-level description of the system design may be generated from thehigh-level description entered in text such as the one illustrated inFIG. 3A. Alternatively, a graphical user interface editor may be used tocapture a high-level description of a system design in block diagramform input by a user to identify the high-level description of thesystem design and to generate a format of the high-level description asthe one illustrated in FIG. 3A.

According to an embodiment of the present invention, an event-drivensimulation kernel such as a SystemC template may be generated from thehigh-level description. The simulation kernel may be used for behavioralsimulation to measure algorithmic changes to the design and forcomputing metrics such as memory and bus efficiency. In this embodiment,data paths may be converted into SystemC channels using the meta-data toidentify register transfers and FIFO channels. Blocks may be convertedinto modules with appropriate port definitions to allow the user toenter behavioral descriptions of functionality. In addition to oralternatively to using the simulation kernel for simulations, thesimulation kernel may be used to statistically model traffic load andlatency. The models generated may be domain specific.

Referring back to FIG. 2A, at 202 a target device design is identified.According to an embodiment of the present invention, the target devicedesign is identified from an architecture description input from a user.The architecture description may include a physical descriptiondescribing instances of individual dice in the system including FPGA,memories, and interposers, and the interconnect between the dice andexternal interfaces. The architecture description may include a physicalfloor plan description of the target device that describes the locationsof columns and rows of core and input output blocks. The architecturedescription may include a description of global routing resources suchas a number or horizontal and vertical lines per row and column, thebandwidth in and out of hardened blocks such as memory blocks, and thephysical delays of wires and blocks. The architecture description mayinclude meta-data about target device resources such as the overheaddelay required to pipeline a data path, push-out delays associated withwidened data paths and congestion, and metrics of routabilitycongestion. It should be appreciated that the architecture descriptionmay be of varying levels. For instance, the architecture description mayinclude a very high level description of a target device. Alternatively,the architecture description may include a very low, detailed leveldescription of the target device. For example, if the target device isan FPGA, a low level description of the target device may include adescription of its underlying cells that include a lookup table andregister. With the target device design identified from the architecturedescription, a model of the target device may be generated in which toimplement the system design. According to an embodiment of the presentinvention, the model of the target device includes the details from thearchitecture description described above.

At 203, the system design is mapped onto the model of the target device.Mapping involves implementing the system design using the resourcesavailable on the target device. Mapping may be performed to account forfixed placement of hard objects on an FPGA or structured ASIC, clockuse, IO connections, wire use, congestion, and timing of the systemdesign on the target device. According to an embodiment of the presentinvention, latency planning may be performed during mapping to explorethe usage of different data path widths for routing signals of a system.

FIG. 4 is a flow chart illustrating a method for performing latencyplanning according to an exemplary embodiment of the present invention.The procedures illustrated in FIG. 4 may be performed at procedure 203shown in FIG. 2A. At 401, it is determined whether selected routingresources on a target device allow data to be transmitted from a sourceto a destination with a bandwidth requirement associated with thedesign. According to an embodiment of the present invention, thebandwidth requirement may be associated with a set of links (routingresources) in the design. If the bandwidth requirement is satisfied,control proceeds to 403. If the bandwidth requirement has not beensatisfied, control proceeds to 402.

At 402, the system design is modified to increase bandwidth. Accordingto an embodiment of the present invention, different methods forproviding the required bandwidth are investigated for the set of linkswith unsatisfied bandwidth requirements. The methods may includepipelining, which will increase the clock speed of the link, but willincrease the latency of the link. The methods may also include widening,which will increase the number of wires going from the source to thedestination or destinations of the link. Widening may also have alatency impact, and will also require more wiring resources, which couldbe a limited resource on a target device. After the modification iscompleted, control proceeds back to 401, where the bandwidth requirementis checked again.

At 403, it is determined whether a latency constraint is satisfied.According to an embodiment of the present invention, the implementationof the set of links is examined to determine whether it meets a latencyconstraint on the set of links. The latency constraint may be a simpleconstraint which is associated with a clock cycle or timing requirement.Alternatively, the latency constraint may be a complex constraint whichis associated with a plurality of links. The examination anddetermination may be performed with a system level simulation during thesystem planning procedure. If the latency constraint is satisfied,control proceeds to 405. If it is not satisfied, control proceeds to404.

At 404, the system design is modified to address latency. According toan embodiment of the present invention, different methods for modifyingthe set of links to adjust the latency are investigated and evaluated.For example, modifications to reduce latency may include reducing adistance traveled by a link, removing pipeline stages, narrowing adatapath, and/or using intrinsically faster interconnect resources. Itshould be appreciated that because these modifications may affectbandwidth as well as latency, the bandwidth requirement is verifiedafter the modifications performed at 404. Control proceeds to 401.

At 405, control terminates the process.

Referring back to FIG. 2A, it should be appreciated that a plurality oftarget device models may be generated at 202 and unique mapping may begenerated for each of the plurality of target device models at 203.

At 204, a description of the mapping is generated. The description ofthe mapping may be a visual representation of the mapping thatillustrates a floor plan, a mapped view showing metrics for resourceuse, or other representation.

FIG. 5 illustrates an exemplary slicing floor plan according to anembodiment of the present invention. FIG. 5 illustrates an example ofthe mapping procedure at 203. The block diagram on the left represents ablock diagram of a system design. The slicing floor plan on the rightprovides a visual representation of how certain blocks from the blockdiagram are to be positioned on a target device floor plan. According toan embodiment of the present invention, the meta-data associated withgeographic resource availability on the target device may be used by themapping procedure to re-size blocks to include the appropriate resourcesor indicate a mismatch between available resources in a physical regionand those needed by the system design.

FIG. 6 illustrates an exemplary alternative mapped view showing metricsfor resource use according to an embodiment of the present invention.FIG. 6 illustrates another example of the mapping procedure at 203. Theblock diagram on the left represents a block diagram of a system design.The alternative mapped view on the right provides a visualrepresentation of high-level data paths as they interconnect certainblocks from the block diagram. The alternative mapped view may alsodisplay information indicating the width and delay/speed of thehigh-level data path as well as the scarcity/abundance of the data path.

It should be appreciated that other visual representation of the resultsof the mapping procedure may be generated and provided to the user. Forexample, a resource allocation chart that illustrates use of deviceresources by module and free resources. In this embodiment, freeresources that reside in another module's floor planned space may bedistinguished from free resources that do not reside in another module'sfloor planned space. Another visual representation that may be generatedmay be a heat-map view that identifies areas on the floor plan whererouting resources are most heavily used.

Referring back to FIG. 2A, at 205, analysis is performed on the systemdesign and target device. According to an embodiment of the presentinvention, power analysis is performed using information associated withresource usage and capacitance in the target device architecturedescription to generate an estimated power consumption value. Activityrates and usability information derived from simulation may also be usedto further improve the accuracy of the estimated power consumptionvalue.

Some target device architecture may be provisioned with a global clockthat is restricted. In these architectures logic must be mapped toregions of the device with common clocking regimes or data paths in oneclock domain need to avoid regions in another clock domain. The analysismay identify any such clock planning and clock-resource violations.

At 206, it is determined whether the results of the mapping aresatisfactory. If the results of the mapping are satisfactory, controlproceeds to 208. If the results of the mapping are not satisfactory,control proceeds to 207.

At 207, it is determined whether modifications may be made to the targetdevice architecture. According to an embodiment of the presentinvention, when the system-level design is used for architectureexploration, a target device architect may make modifications to thetarget device to improve the implementation of the system design on thetarget device. Modifications to the target device may include changingthe positioning of the input output ring, positioning the location ofmemory interfaces, and increasing or decreasing the amounts or types ofrouting resources available on the target device. If modifications areto be made to the target device, control returns to 202 and themodifications are entered.

If modifications are not to be made to the target device, controlreturns to 201 to allow the user to modify the system design. Accordingto an embodiment of the present invention, when the system-level designis used for design planning, a user may make modifications to the systemdesign to improve the implementation of the system design on the targetdevice. When modifications are not to be made to the target device, thesame target device entered previously at 202 may be used again.

At 208, control terminates the process.

Embodiments of the present invention may be used as a system-leveldesign tool that allows a user to obtain feedback regarding the mappingof a system design without requiring implementing the system design inRTL for place and route. Embodiments of the present invention allow forthe planning of a system design by performing a floor planning whichtakes into account data path analysis, wire planning, and thesufficiency of resources. It should be appreciated that with referenceto the process illustrated in FIG. 2A, several target devices may beidentified at 202 and a single system design may be mapped onto aplurality of target device models at 203. This would allow a user toobtain a visual representation of how a single system design may bemapped onto different target device architectures and allow the user toselect one of the system architectures to modify and eventuallyimplement.

FIG. 2B is a flow chart illustrating a method for performing earlyplanning with a plurality of target devices according to an exemplaryembodiment of the present invention.

At 201, a system design is identified. According to an embodiment of thepresent invention, the system design is identified from inputs receivedfrom a user. The system design may be a high-level description of thesystem that is not a complete RTL design. The high-level description ofthe system may include similar characteristics as those described at 201in FIG. 2A.

At 202-1 to 202-N, a target device design is identified, where N mayrepresent any number of target devices. According to an embodiment ofthe present invention, the target device design is identified from anarchitecture description input from a user. The architecture descriptionmay include similar characteristics as those described at 202 in FIG.2A. With the target device design identified from the architecturedescription, a model of the target device may be generated in which toimplement the system design. According to an embodiment of the presentinvention, the model of the target device includes the details from thearchitecture description described above.

At 203-1 to 203-N, the system design is mapped onto each of the model ofthe target devices generated at 202-1 to 202-N respectively. The mappingprocedure performed at 203-1 to 203-N may be similar to the mappingprocedure described with reference to 203 in FIG. 2A.

At 204-1 to 204-N, a description of the mapping is generated for each ofthe mappings performed at 203-1 to 203-N respectively. The descriptionof the mapping may be a visual representation of the mapping thatillustrates a floor plan, a mapped view showing metrics for resourceuse, or other representation.

At 205-1 to 205-N, analysis is performed on the system design and eachof the target devices generated at 203-1 to 203-N respectively. Theanalysis procedure performed at 205-1 to 205-N may be similar to theanalysis procedure described with reference to 205 in FIG. 2A.

At 206-1 to 206-N, it is determined whether the results of therespective mappings are satisfactory. If the results of the mapping ontoa target device is satisfactory, control proceeds to one of 208-1 to208-N corresponding to the target device. If the results of the mappingare not satisfactory, control proceeds to one of 207-1 to 207-N.

At 207-1 to 207-N, it is determined whether modifications may be made tothe respective target device architecture. According to an embodiment ofthe present invention, when the system-level design is used forarchitecture exploration, a target device architect may makemodifications to the target device to improve the implementation of thesystem design on the target device. Modifications to the target devicemay include changing the positioning of the input output ring,positioning the location of memory interfaces, and increasing ordecreasing the amounts or types of routing resources available on thetarget device. If modifications are to be made to the target device,control returns to 202 and the modifications are entered.

If modifications are not to be made to the target device, controlreturns to 201 to allow the user to modify the system design. Accordingto an embodiment of the present invention, when the system-level designis used for design planning, a user may make modifications to the systemdesign to improve the implementation of the system design on the targetdevice. When modifications are not to be made to the target device, thesame target device entered previously at 202-1 to 202-N may be usedagain.

At 208, further analysis may be performed to determine which of thetarget device designs offer the best solution for the system design.

Embodiments of the present invention may be used as an architectureexploration tool that allows a user to test various system designs on atarget device architecture and to determine what modifications to thetarget device may improve the implementation of the various systemdesigns. Solutions that may be sought in modifications made by the userinclude whether to implement memory blocks in columns or alternativearrangements, the amount of wiring to provide a routing fabric of thetarget device, and the types of interconnect to provide on the targetdevice. It should be appreciated that with reference to the processillustrated in FIG. 2A, a plurality of system designs may be identifiedat 201 and mapped onto a single target device models at 203. This wouldallow a user to obtain a visual representation of how a particulartarget device architecture is capable of implementing a plurality ofdifferent system designs, and allow the user to see how modifications toa particular target device architecture impacts the plurality of systemdesigns.

FIGS. 1, 2A-2B, and 4 are flow charts that illustrate embodiments of thepresent invention. Some of the techniques illustrated may be performedsequentially, in parallel or in an order other than that which isdescribed and that the procedures described may be repeated. It shouldbe appreciated that not all of the techniques described are required tobe performed, that additional techniques may be added, and that some ofthe illustrated techniques may be substituted with other techniques.

FIG. 7 is a block diagram of an exemplary computer system 700 in whichan example embodiment of the present invention resides. The computersystem 700 may be used to implement a system designer such as an EDAtool. The computer system 700 includes a processor 701 that processesdata signals. The processor 701 is coupled to a bus 710 that transmitsdata signals between components in the computer system 700. The bus 710may be a single bus or a combination of multiple buses. The computersystem 700 includes a memory 702. The memory 702 may be a dynamic randomaccess memory device, a static random access memory device, and/or othermemory device. The memory 702 may store instructions and coderepresented by data signals that may be executed by the processor 701. Adata storage device 703 is coupled to the bus 710. The data storagedevice 703 may be a hard disk drive, a floppy disk drive, a CD-ROMdevice, a flash memory device or other mass storage device.

A network controller 704 is coupled to the bus 710. The networkcontroller 704 may link the computer system 700 to a network ofcomputers (not shown) and supports communication among the machines. Adisplay device controller 705 is coupled to the bus 710. The displaydevice controller 705 allows coupling of a display device (not shown) tothe computer system 700 and acts as an interface between the displaydevice and the computer system 700. An input interface 706 is coupled tothe bus 710. The input interface 706 may be, for example, a keyboardand/or mouse controller or other input interface. The input interface706 allows coupling of an input device to the computer system 700 andtransmits data signals from an input device to the computer system 700.It should be appreciated that computer systems having a differentarchitecture or having different components may also be used toimplement the computer system 700.

According to an embodiment of the present invention, a system designer720 may reside in memory 702 and be executed by the processor 701. Thesystem designer 720 may operate as a system-level design tool forperforming design planning and target device architecture exploration.The design tool allows for design planning and decision making prior tomaking key decisions that lock down algorithms and structures of adesign. The design tool may also be used to model designs for thepurpose of more effectively architecting next-generation target devices.The design tool may be used for wire-planning and resource management ona high-level design. Designs may be defined using a high-leveldescription instead of a detailed hardware description such as RTL. Thehigh-level description may be mapped to one or more target devicearchitectures and the mapping may be output to a user such as a systemdesigner or target device architect to evaluate. The system designer 720may also operate to synthesize, map, place and route the system onto atarget device.

FIG. 8 illustrates a system designer 800 according to an embodiment ofthe present invention. The system designer 800 may be an EDA tool fordesigning a system on a target device such as an FPGA, structuredapplication-specific integrated circuit (ASIC), ASIC, or othercircuitry. FIG. 8 illustrates modules implementing an embodiment of thesystem designer 800. According to one embodiment, the modules representsoftware modules and system design may be performed by a computer systemsuch as the one illustrated in FIG. 7 executing sequences ofinstructions represented by the modules shown in FIG. 8. Execution ofthe sequences of instructions causes the computer system to supportsystem design as will be described hereafter. In alternate embodiments,hard-wire circuitry may be used in place of or in combination withsoftware instructions to implement embodiments of present invention.Thus, embodiments of present invention are not limited to any specificcombination of hardware circuitry and software.

The system designer 800 includes a system designer manager 810. Thedesigner system manager 810 is connected to and transmits data betweenthe other components of the system designer 800. The system designermanager 810 provides a user interface that allows a user to input datainto the system designer 800. According to an embodiment of the presentinvention, a description of a system may be input into the systemdesigner by the user. The description of the system may be a high-leveldescription generated by a user.

The system designer 800 includes a system design identification (ID)unit 815. The system design unit 815 identifies a system from inputsreceived from a user. The system design may be a high-level descriptionof the system that is not a complete RTL design. The high-leveldescription of the system may describe components of the system ashigh-level blocks and include information regarding their resourceusage, data path descriptions which include the width and speedrequirements of data path between the high-level blocks, system-levelmeta-data, and block-level meta-data. The high-level description of thesystem may also provide SystemC or other description of thecycle-accurate/approximate behavior of a block that may be used inconstructing dynamic simulation.

The system designer 800 includes a target device modeling unit 820. Thetarget device modeling unit 820 identifies a target device from anarchitecture description input from the user. The architecturedescription may include a physical description, a floor plandescription, a description of global routing resources, and/or meta-dataabout target device resources. With the target device identified fromthe architecture description, a model of the target device may begenerated in which to implement the system design.

The system designer 800 includes a mapping unit 825 that maps the systemdesign onto the model of the target device. Mapping involvesimplementing the system design using the resources available on thetarget device. Mapping may be performed to account for wire use,congestion, and timing of the system design on the target device.According to an embodiment of the present invention, latency planning,as described with reference to FIG. 5, may be performed during mappingto explore the usage of different data path widths for routing signalsof a system. The latency planning may be performed by a latency planningunit in the mapping unit 825.

The system designer 800 includes a mapping description unit 830. Themapping description unit 830 generates a description of the mappingperformed by the mapping unit 825. The description of the mapping may bea visual representation of the mapping that illustrates a floor plan, amapped view showing metrics for resource use, or other representation.Based upon an evaluation of the mapping, a user may modify the systemdesign and/or the target device and perform another mapping to furtherevaluate the system design and/or target device architecture.

The system designer 800 includes a RTL generator unit 835. The RTLgenerator unit 835 generates an RTL description of the system designidentified and evaluated. According to an embodiment of the presentinvention, the RTL is used to generate a hardware description language(HDL) design definition to describe the system. The HDL describes theoperation of the system to be programmed on the target device. The HDLdescription provides high-level representations of a circuit in terms ofthe flow of signals (or transfer of data) between hardware registers,and the logic operations performed on those signals.

The system designer 800 includes a synthesis unit 840 that performssynthesis. The synthesis unit 840 generates a logic design of a systemto be implemented on the target device. According to an embodiment ofthe system designer 800, the synthesis unit 840 takes a conceptual HDLdesign definition and generates an optimized logical representation ofthe system. The optimized logical representation of the system generatedby the synthesis unit 840 may include a representation that has areduced number of functional blocks and registers, such as logic gatesand logic elements, required for the system. Alternatively, theoptimized logical representation of the system generated by thesynthesis unit 840 may include a representation that has a reduced depthof logic and that generates a lower signal propagation delay.

The synthesis unit 840 also performs technology mapping. Technologymapping involves determining how to implement the functional blocks andregisters in the optimized logic representation utilizing specificresources such as cells on a target device thus creating an optimized“technology-mapped” netlist. The technology-mapped netlist illustrateshow the resources (cells) on the target device are utilized to implementthe system. In an embodiment where the target device is an FPGA, thetechnology-mapped netlist may include cells such as logic array blocks(LABs), registers, memory blocks, digital signal processing (DSP)blocks, input output (JO) elements or other components.

The system designer 800 includes a placement unit 845 that processes theoptimized technology-mapped netlist to produce a placement for each ofthe functional blocks. The placement identifies which components orareas on the target device are to be used for specific functional blocksand registers.

The system designer 800 includes a routing unit 850 that performsrouting. The routing unit 850 determines the routing resources on thetarget device to use to provide interconnection between the componentsimplementing functional blocks and registers of the logic design.

The system designer 800 includes an assembly unit 855 that performs anassembly procedure that creates a data file that includes the design ofthe system generated by the system designer 800. The data file may be abit stream that may be used to program the target device. The assemblyunit 855 may output the data file so that the data file may be stored oralternatively transmitted to a separate machine used to program thetarget device. It should be appreciated that the assembly unit 855 mayalso output the design of the system in other forms such as on a displaydevice or other medium.

It should be appreciated that embodiments of the present invention maybe provided as a computer program product, or software, that may includea computer-readable or machine-readable medium having instructions. Theinstructions on the computer-readable or machine-readable medium may beused to program a computer system or other electronic device. Themachine-readable medium may include, but is not limited to, floppydiskettes, optical disks, CD-ROMs, and magneto-optical disks or othertype of media/machine-readable medium suitable for storing electronicinstructions. The techniques described herein are not limited to anyparticular software configuration. They may find applicability in anycomputing or processing environment. The terms “computer-readablemedium” or “machine-readable medium” used herein shall include anymedium that is capable of storing or encoding a sequence of instructionsfor execution by the computer and that cause the computer to perform anyone of the methods described herein. Furthermore, it is common in theart to speak of software, in one form or another (e.g., program,procedure, process, application, module, unit, logic, and so on) astaking an action or causing a result. Such expressions are merely ashorthand way of stating that the execution of the software by aprocessing system causes the processor to perform an action to produce aresult.

FIG. 9 illustrates a device 900 that may be used to implement a targetdevice according to an embodiment of the present invention. The device900 is a field programmable gate array (FPGA) that includes a pluralityof logic-array blocks (LABs). Each LAB may be formed from a plurality oflogic blocks, carry chains, LAB control signals, look up table (LUT)chain, and register chain connection lines. A logic block is a smallunit of logic providing efficient implementation of user logicfunctions. A logic block includes one or more combinational cells, whereeach combinational cell has a single output, and registers. According toone embodiment of the present invention, the logic block may operatesimilarly to a logic element (LE), such as those found in the Stratix orCyclone devices manufactured by Altera® Corporation, or a combinationallogic block (CLB) such as those found in Virtex devices manufactured byXilinx Inc. In this embodiment, the logic block may include a four inputLUT with a configurable register. According to an alternate embodimentof the present invention, the logic block may operate similarly to anadaptive logic module (ALM), such as those found in Stratix devicesmanufactured by Altera Corporation. LABs are grouped into rows andcolumns across the device 900. Columns of LABs are shown as 911-916. Itshould be appreciated that the logic block may include additional oralternate components.

The device 900 includes memory blocks. The memory blocks may be, forexample, dual port random access memory (RAM) blocks that providededicated true dual-port, simple dual-port, or single port memory up tovarious bits wide at up to various frequencies. The memory blocks may begrouped into columns across the device in between selected LABs orlocated individually or in pairs within the device 900. Columns ofmemory blocks are shown as 921-924.

The device 900 includes digital signal processing (DSP) blocks. The DSPblocks may be used to implement multipliers of various configurationswith add or subtract features. The DSP blocks include shift registers,multipliers, adders, and accumulators. The DSP blocks may be groupedinto columns across the device 900 and are shown as 931.

The device 900 includes a plurality of input/output elements (IOEs) 940.Each IOE feeds an IO pin (not shown) on the device 900. The IOEs 940 arelocated at the end of LAB rows and columns around the periphery of thedevice 900. Each IOE may include a bidirectional IO buffer and aplurality of registers for registering input, output, and output-enablesignals.

The device 900 may include routing resources such as LAB localinterconnect lines, row interconnect lines (“H-type wires”), and columninterconnect lines (“V-type wires”) (not shown) to route signals betweencomponents on the target device.

In the foregoing specification, embodiments of the invention have beendescribed with reference to specific exemplary embodiments thereof. Itwill, however, be evident that various modifications and changes may bemade thereto without departing from the broader spirit and scope of theembodiments of the invention. The specification and drawings are,accordingly, to be regarded in an illustrative rather than restrictivesense.

What is claimed is:
 1. A method for designing a system on a targetdevice: mapping a high-level description of the system onto a model of atarget device prior to generating a register transfer level descriptionof the system; and generating a visual representation of the mapping. 2.The method of claim 1, wherein the mapping of the high-level descriptionaccounts for wire use of the system and wire resources on the targetdevice.
 3. The method of claim 1, wherein the mapping of the high-leveldescription accounts for timing requirements of the system and routingcongestion.
 4. The method of claim 1, wherein the high-level descriptioncomprises identities of components in the system and their resourceusage.
 5. The method of claim 1, wherein the high-level descriptioncomprises width and speed requirement of data paths between componentsin the system.
 6. The method of claim 1, wherein the high-leveldescription comprises system-level meta-data describing latencytolerances of data paths between components in the system and uses ofthe data paths.
 7. The method of claim 1, wherein the high-leveldescription comprises block-level meta-data describing a component'srouting porosity and maximum frequency.
 8. The method of claim 1,further comprising mapping modifications to the high-level of thedescription onto the target device.
 9. The method of claim 1, furthercomprising: mapping the high-level of the description of the system ontoa different model of the target device prior to generating the RTL ofthe system; and generating a visual representation of the mapping ontothe different model of the target to the user.
 10. The method of claim1, further comprising performing latency planning.
 11. A non-transitorycomputer readable medium including a sequence of instructions storedthereon for causing a computer to execute a method comprising:generating a plurality of models of a target device from a descriptioninput by a user; mapping a high-level description of a system onto themodels of the target device; and generating a visual representation ofthe mappings.
 12. The non-transitory computer readable medium of claim11, wherein the description input by the user comprises one or morephysical floor plan descriptions of the target device.
 13. Thenon-transitory computer readable medium of claim 11, wherein thedescription input by the user comprises a description of a range ofglobal routing resources.
 14. The non-transitory computer readablemedium of claim 11, wherein the description input by the user comprisesdelay metrics associated with pipelining data paths and widening datapaths.
 15. The non-transitory computer readable medium of claim 11,wherein the description input by the user describes a range ofwire-widths that may be implemented by the target device.
 16. Thenon-transitory computer readable medium of claim 11, wherein thehigh-level description of the system is at a level higher than aregister transfer level description.
 17. The non-transitory computerreadable medium of claim 11, wherein the visual representation of themapping comprises a slicing floor plan.
 18. The non-transitory computerreadable medium of claim 11, wherein the visual representation of themapping comprises a mapped view illustrating resource use.
 19. Thenon-transitory computer readable medium of claim 11, wherein the methodfurther comprises: modifying one of the models of the target device; andmapping the high-level description of the system onto the modifiedmodel.
 20. The non-transitory computer readable medium of claim 11,wherein the method further comprises performing latency planningcomprises by: determining whether bandwidth requirements are satisfied;and modifying one of the plurality of models to increase bandwidthsupport in response to determining that the bandwidth requirements arenot satisfied.
 21. The non-transitory computer readable medium of claim11, wherein the method further comprises performing latency planningcomprises by: determining whether a latency constraint is satisfied; andmodifying one of the plurality of models in response to determining thatthe latency constraint is not satisfied.
 22. A system designer,comprising: a mapping unit operable to map a high-level description ofthe system onto a model of a target device prior to generating aregister transfer level description of the system; and a mappingdescription unit operable to generate a visual representation of themapping.
 23. The system designer of claim 22 further comprising a targetdevice modeling unit operable to generating the model of the targetdevice from a description input by a user.
 24. The system designer ofclaim 22, wherein the mapping unit is operable to map the high-level ofthe description of the system onto a different model of the targetdevice
 25. The system designer of claim 22, wherein the mapping unit isoperable to map modifications to the high-level of the description ontothe model of the target device.